A ball is thrown vertically downwards from a height of 20 m with an initial velocity v_0. It collides with the ground, loses 50 \% of its energy in collision and rebounds to the same height. The init…

Question

A ball is thrown vertically downwards from a height of 20 m with an initial velocity v_0. It collides with the ground, loses 50 \% of its energy in collision and rebounds to the same height. The initial velocity v_0 is (Take, g=10 ms^-2)

Accepted Answer

Correct answer: B. (b) Suppose a ball rebounds with speed v, v= 2 gh= 2 10 20=20 m/s Energy of a ball just after rebound, E= 12mv^2=200 m As, 50 \% of energy loses in collision means just before collision energy is 400 m . According to law of conservation of energy, we have 12mv_0^2+ mgh=400 m ⇒ 12mv_0^2+m 10 20=400 m ⇒v_0=20 m/s

$A ball is thrown vertically downwards from a height of 20 m with an initial velocity v_{0} . It collides with the ground, loses 50 % of its energy in collision and rebounds to the same height. The initial velocity v_{0} is (Take, g = 10 ms^{- 2})$

Solution

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